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Abstract

Abstract: Advances in swept source laser technology continues to increase the imaging speed of swept-source optical coherence tomography (SS-OCT) systems. These fast imaging speeds are ideal for microvascular detection schemes, such as speckle variance (SV), where interframe motion can cause severe imaging artifacts and loss of vascular contrast. However, full utilization of the laser scan speed has been hindered by the computationally intensive signal processing required by SS-OCT and SV calculations. Using a commercial graphics processing unit that has been optimized for parallel data processing, we report a complete high-speed SS-OCT platform capable of real-time data acquisition, processing, display, and saving at 108,000 lines per second. Subpixel image registration of structural images was performed in real-time prior to SV calculations in order to reduce decorrelation from stationary structures induced by the bulk tissue motion. The viability of the system was successfully demonstrated in a high bulk tissue motion scenario of human fingernail root imaging where SV images (512 × 512 pixels, n = 4) were displayed at 54 frames per second.

Time expenditure of each processing step preformed on the GPU in the order of execution as shown in Thread 2 of Fig. 2. The total average processing time was 3.02ms for each SV image (512 × 512 pixels, n = 4) with registration image size of 256 × 256. memcpyHtoD and memcpyDtoH are data transfer to and from the GPU, respectively.

2D SV projection image (a) without and (b) with structural image realignment using subpixel image registration algorithm. Motions during imaging appeared as periodic horizontal striations (indicated by the white arrows on left hand side) that increased the noise floor, while lowering the vascular contrast and overall image quality. The image registration algorithm reduced these effects, while improving the overall image quality. Scale bar is 500μm.